San Juan County, Utah was established in 1880 and named for the San Juan River (itself named for St. John the Baptist by Spanish explorer, Juan Rivera, in 1765)! Its county seat is Monticello, and its fair is also held in Monticello! You might recognize the Utah part of Four Corners, Monument Valley, Lake Powell, Canyonlands National Park, and four national monuments (Natural Bridges, Rainbow Bridge, Hovenweep, and Bears Ears), which are located in this county!